EXCEL VBAメモ - バイナリファイルアクセス

LOFでファイルサイズを取得できる。Get,Put共、第2引数で位置を指定、第3引数のサイズ分だけ読み書きを行う。
読み取り時bufの不足分は0で埋められる。

Sub accessBinFile()
    Dim fNo As Long
    Dim fName As String
    Dim buf(0 To 4) As Byte
    Dim pos As Long, i As Long
    Dim s As String
    
    fNo = FreeFile
    fName = ThisWorkbook.Path & "\sample.txt"
    
    ' Textで元データ書き込み
    Open fName For Output As #fNo
    Print #fNo, "0123"
    Print #fNo, "ABCD"
    Close #fNo
    
    ' Binaryで読み込み
    pos = 1
    Open fName For Binary As #fNo
    Do Until pos > LOF(fNo)  ' #は不要
        Get #fNo, pos, buf
        s = ""
        For i = 0 To UBound(buf)
            s = s & Right("0" & Hex(buf(i)), 2) & " "
        Next
        MsgBox s
        pos = pos + UBound(buf) + 1
    Loop
    Close #fNo
    
    ' 2Byte目を"9"に書き換え
    Open fName For Binary As #fNo
    Put #fNo, 2, CByte(Asc("9"))
    Close #fNo
End Sub